Almost all tropical cyclones making landfall in the United States
spawn at least one tornado, provided enough of the TC's circulation moves
over land. This implies that Gulf coast landfalling TC's are more likely
to produce tornadoes than Atlantic coast TC's that "sideswipe" the
coastline. The rate at which TC's produce tornadoes (waterspouts) over
the ocean is unknown, although Doppler radars have identified many cases
where storm cell rotation suggestive of the presence of tornadoes was
observed over water, and there have been a number of cases where
TC-spawned waterspouts have been witnessed from shore, with some of these
coming ashore as tornadoes (McCaul, 1991);
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